“Bilingual” neurons may reveal the secrets of brain disease

News

Published: 18Mar2011

Major breakthrough in understanding of brain function

Major breakthrough in understanding of brain
function

A team of researchers from the University of Montreal and McGill
University have discovered a type of “cellular bilingualism” – a
phenomenon that allows a single neuron to use two different methods
of communication to exchange information. “Our work could
facilitate the identification of mechanisms that disrupt the
function of dopaminergic, serotonergic and cholinergic neurons in
diseases such as schizophrenia, Parkinson’s and depression,” wrote
Dr. Louis-Eric Trudeau of the University of Montreal’s Department
of Pharmacology and Dr. Salah El Mestikawy, a researcher at the
Douglas Mental Health University Institute and professor at
McGill’s Department of Psychiatry. An overview of this discovery
was published in the Nature Reviews Neuroscience
journal.

Their results show that many neurons in the brain are able to
control cerebral activity by simultaneously using two chemical
messengers or neurotransmitters. This mode of communication is
known as “cotransmission.” According to Dr. Trudeau, “the neurons
in the nervous system – both in the brain and in the peripheral
nervous system – are typically classified by the main transmitter
they use.” For example, dopaminergic neurons use dopamine as a
transmitter to communicate important information for many different
phenomena such as motivation and learning. The malfunction of these
neurons is involved in serious brain diseases such as schizophrenia
and Parkinson’s. “Our recent research, carried out in part with Dr.
Laurent Descarries at the University of Montreal, shows that
dopaminergic neurons use glutamate as a second transmitter. That
means they are able to transmit two types of messages in the brain,
on two time scales: a fast one for glutamate and a slower one for
dopamine.”

Other research conducted by Dr. Salah El Mestikawy’s team at the
Douglas Mental Health University Institute observed the same kind
of bilingualism in brain neurons that use serotonin, a group of
cells that communicate important information for controlling mood,
aggression, impulsivity and food intake, and also those that use
acetylcholine, an important messenger for motor skills and memory
that is unbalanced by Parkinson’s disease, antipsychotic drugs and
in drug addiction.

Joint studies carried out with their colleague Dr. Åsa
Wallen-Mackenzie at Uppsala University in Sweden and published
recently in the Proceedings of the National Academy of Sciences
journal suggest that the secretion of glutamate by dopaminergic
neurons could, for example, be involved in the behavioural effects
of psychostimulants such as amphetamines and cocaine. “We know very
little about the role of cotransmission in disease and the
regulation of behaviour, however,” Dr. Trudeau warned. “That will
have to be the subject of future studies.”

The studies were funded by grants from the National Alliance for
Research on Schizophrenia and Depression, the Canadian Institutes
of Health Research, the Swedish Foundation for International
Cooperation in Research and Higher Education and the Agence
Nationale pour la Recherche (France).